In order to reduce the transmission line loss in an extremely high frequency spectrum microwave transmission system, beam waveguide structures, namely schemes employing mirrors for reflecting RF microwave energy from one point to another, have been proposed. Since the mirrors direct or guide the microwave frequency along a prescribed path, the transmission arrangement may be referred to as a waveguide. Because the microwave energy is guided by the use of mirrors, rather than conducting walls, as is employed in typical microwave transmission schemes, the loss of energy over the transmission path can be significantly reduced as compared with conventional waveguide. This is especially true in the EHF spectrum where the size of the mirrors employed may be made small enough for a beam waveguide system to be a practical alternative to conventional and overmoded waveguide. For example, a system designed for use at 30 GHz over a path length of 80 feet has been calculated to have a loss of only 1 dB while the same system using conventional waveguide has been measured to suffer a loss of at least 12 dB.
On the other hand, previously proposed beam waveguide configurations have been found to be unattractive because of the size of the components required (something which is less of a problem at EHF), alignment of the mirrors, its lack of versatility, and the fact that each site or mirror mounting station requires its own particular design. As a result, beam waveguide has not yet lent itself for use in mobile systems requiring rapid installation time and flexibility in site layout.